Nowadays, amplification and detection of nucleic acids such as DNA is used in different approaches. In many routine diagnostics the analysis of the amplified nucleic acids is conducted via capillary electrophoresis. This method separates the analytes according to the length of the DNA molecules and detects them via fluorescent labels. In the resulting electropherograms peaks identify DNA molecules of a certain lengths. However, due to artefacts, such as degraded products or primers, small peaks above the baseline (background peaks) appear resulting in a loss of sensitivity. These background peaks represent free fluorescent labels and/or short oligonucleotides (1 to 8 bases) comprising the labels.
One problem underlying the present invention is to provide labeled oligonucleotides with an increased stability to reduce the background peaks and to increase sensitivity of detection.